When your crosshair meets up with the bobber of a fishing rod while casted, the crosshair turns to a light blue, translucent color.
I am not sure if this is intended or a bug but it has not been reported according to my research beforehand..
MC-106544
Crosshair Bobber Glitch
Resolved
Works As Intended
0
(Unassigned)
Unconfirmed
Minecraft 1.10.2, Minecraft 16w32a, Minecraft 16w32b, Minecraft 16w33a
Retrieved
Intended.
The crosshair is rendered with XOR to have visibility on any background.